Патент USA US3062544код для вставки
Nov. 6, 1962 R. w. BENSON ETAL 3,052,534 SHEET FEED MECHANISM Filed July 5, 1961 12 Sheets-Sheet 1 I l | l I . 35 14 N l | \ INVENTORS ROBERT W. BENSON JOHN F. WIRLEY .4 T TORNE V NQV- 6, 1962 R. w. BENSON ETAL 3,062,534 SHEET FEED MECHANISM Filed July 5, 1961 ' l2, Sheets-“Sheet 2 INVENTORS I ROBERT W. BENSON JOHN F. WIRLEY A T TORNE V Nov. 6, 1962 R. w. BENSON ETAL 3,062,534 SHEET FEED MECHANISM Filed July 3, 1961 12 Sheets-Sheet 3 INVENTORS ROBERT W. BENSON JOHN F. WIRLEY ylM/w NOV- 6, 1962 R. w. BENSON ETAL 3,062,534 SHEET FEED MECHANISM Filed July 3, 1961 l2 Sheets-Sheet 4 INVENTOR? ROBERT W. BENSON JOHN F. WIRLEY ATTORNEY Nov. 6, 1962 R. w. BENSON ETAL 3,062,534 SHEET FEED MECHANISM Filed July 3, 1961 l2 Sheets~$heet 5 mil/111111111117)?’ I u I l L________.-_____... ‘_ INVENTORS ROBERT W. BENSON JOHN F. WIRLEY A TTOR/VEV N0“ 6, 1962 R. w. BENSON ETAL 3,062,534 T FEED MEC A Filed July 5, 1961 12 Sheets~$heet 6 INVENTORS ROBERT W. BENSON JOHN F. WIRLEY Nov. 6, 1962 R. w. BENSON ETAL 3,062,534 SHEET FEED MECHANISM Filed July :5, 1961 l2 Sheet5"$heet 7 495 9 ixxx/ %, INVENTORS ROBERT w. BENSON JOHN F- WIRLEY ATTORNEY Nov. 6, 1962 R. w. BENSON ETAL 3,062,534 SHEET FEED MECHANISM Filed July 3, 1961 12 Sheets-Sheet 8 F/G8 4 24,422 449 INVENTORS ROBERT W. BENSON JOHN F. WIRLEY ATTORNEY NOV- 6, 1962 R. w. BENSON ETAL 35062534 - SHEET FEED MECHANISM Filed July 5, 1961 12 Sheets-Sheet 9 INVENTOILS ROBERT W. BENSON JOHN F. WIRLEY Nov. 6, 1962 R, w_ BENSON ETAL 3,062,534 SHEET FEED MECHANISM Filed July 3, 1961 .12 Sheets~$heet l0 INVENTOR5 ROBERT W. BENSON NOV. 6, 1962 R. w. BENSON ETAL 3,062,534 SHEET FEED MECHANISM Filed July 3, 1961 .12 Sheets-Sheet ll F/ G‘. / 6 53/ 533 $5" 544 542 53 537 @, ~ 534 54 4 535 as 8 535 53a '543 ll—_ ___1 F/ G. / 8 INVENTORS BY ROBERT W. BENSON JOHN E WIRLEY 7“ 10/94» ATTORNEY Nov. 6, 1962 R. W. BENSON ETAL 3,062,534 SHEET FEED MECHANISM Filed July 3, 1961 12 Sheets~$heet 12 h IWQ 502 B INVENTORS ROBERT W. BENSON JOHN E WIRLEY Arromgf _ aw re‘ ire States Patent ‘l1v ,. IC€ 3,062,534 Patented Nov. 6, 1962 2 1 A further object of this invention is to improve sheet 3,062,534 SHEET FEED MECHANISM Robert W. Benson, Rochester, and John F. Wirley, Web ster, N.Y., assignors to Xerox Corporation, Rochester, N.Y., a corporation of New York Filed July 3, 1961, Ser. No. 121,784 3 Claims. (Cl. 271-—36) This invention relates in general to xerographic ap paratus and, in particular, to a sheet transfer material feeding mechanism by which sheets of transfer material are fed seriatim to a xerographic drum. More speci?cally, the invention relates to an improved sheet transfer material feeding mechanism that is par ticularly adapted for use in xerographic reproducing 15 machines, and is also suitable for use with comparable types of devices. In the process of xerography, for example, as disclosed in either Carlson Patent 2,297,691, issued October 6, 1942, or in Carlson Patent 2,357,809, issued September 12, 1944, a xerographic plate, comprising a layer of photoconductive insulating material on a conductive backing, is given a uniform electric charge over its sur face and is then exposed to the subject matter to be reproduced, usually by conventional projection tech niques. This exposure discharges the plate areas in ac cordance with the radiation intensity that reaches them and thereby creates an electrostatic latent image on or in the plate coating. Development of the image is effected with developer feeder mechanisms for use in a xerographic apparatus having a movable xerographic plate capable of having a xerographic image formed anywhere on its photoconduc tive surface. For a better understanding of the invention as well as other objects and further features thereof, reference is had to the following detailed description of the inven tion to be read in connection with the accompanying drawings, wherein: FIG. 1 illustrates schematically a preferred embodi ment of a xerographic apparatus adapted for continuous and automatic operation and incorporating an optical scanning mechanism; FIG. 2 is a right-hand perspective view of the xero graphic apparatus with parts of the desk covering broken away to show the arrangement of the xerographic machine elements; FIG. 3 is a left-hand perspective view of the xero graphic apparatus with the parts of the desk covering broken away to show the arrangement of the xerographic machine elements; FIG. 4 is a right-hand perspective view, partly in sec tion, of the paper feed mechanism of the apparatus; FIG. 5 is a side sectional view of the image transfer station of the xerographic appartus and associated elements; FIG. 6 is a right-hand perspective view of the paper feed tray removed from the xerographic apparatus; 30 FIG. 7 is a top view of the paper feed tray; FIG. 8 is a sectional view taken along line 8—8 of material or developers which comprise, in general, a mix ture of a suitable pigmented or dyed electroscopic powder, FIG. 7; FIG. 9 is a sectional view taken along line 9—9 of hereinafter referred to as toner, and a granular carrier material, which later functions to carry and to generate FIG. 7; FIG. 10 is a sectional view taken along line 10—10 triboelectric charges on the toner. More exactly, the 35 function of the granular material is to provide the me of FIG. 7; FIG. 11 is a sectional view taken along line 11-11 of chanical control of the powder, or to carry the powder to an image surface and, simultaneously, to provide FIG. 7; FIG. 12 is a sectional view taken along line 12--12 of almost complete homogeneity of charge polarity. In the development of the image, the toner powder is brought 40 FIG. 7; into surface contact with the coating and is held thereon electrostatically in a pattern corresponding to the elec tray with parts broken away to show the arrangement of trostatic latent image. Thereafter, the developed xero the back guide assembly; FIG. 13 is a bottom view of a portion of the paper FIG. 14 is a sectional view of the paper separator roller graphic image is usually transferred to a support or trans fer material to which it may be ?xed by any suitable 45 and associated elements; FIG. 15 is a sectional view of the paper separator roller means. Since the disclosure of the basic concept of xerography by Carlson, a variety of machines and devices have been drive and tensioning elements; proposed to incorporate such teachings in a manner to form copy xerographicaily on a commercial basis. For the clutch mechanism of the invention for controlling the operation of the paper feed system; the most part, each of such devices has been speci?cally designed to the solution of a particular reproduction problem and, for the most part, has been limited to the, particular use intended. Although certain of these FIG. 17 is a sectional View of the clutch mechanism of the paper feed system; FIG. 18 is a side view of the electromagnetic clutch mechanism and its contacts, with parts broken away to FIG. 16 is a front view of a preferred embodiment of machines are presently in wide commercial use, none 55 show details of the contacts; and, can be considered to be of general application of the type required in most business offices. For example, prior FIG. 19 is a simple schematic electrical wiring diagram of the clutch circuit. Referring now to the drawings, there is shown in FIGS. art machines are usually limited as to the type of origi 1, 2 and 3, a xerographic apparatus used for producing nal that may be used therewith, or as to the type and size of transfer material that can be employed therein, or as 60 xerographic reproductions from a stationary original, the to the ?exibility of operation of the machine itself. It is therefore the principal object of this invention to improve the sheet feeding mechanism for use in auto original being either transparent, translucent or opaque copy, Whether in the form of single sheets, books, or in three-dimensional form. To conform to modern o?ice matic xerographic apparatus in which a reusable xero decor the xerographic apparatus is adapted for installa graphic plate may successively be charged, exposed and developed, and in which the developed image may readily tion in a suitable desk, constructed so that an operator seated at the desk may conveniently control all opera be transferred to a sheet of transfer material, such as tions of the apparatus. paper or similar material, and thereby permit continuous reuse of the xerographic plate. Another object of this invention is to improve sheet feeding mechanisms for feeding sheets seriatim to a rotating drum independently of the drum’s rotative cycle. The desk, generally designated 1, constructed in a con ventional manner, has mounted on the top and in the right hand corner thereof, a main control panel for initiating the operation of the machine and for selecting and indi cating the number of reproductions to be made, and a » 3,062,534 3 collecting tray 2 for ?nished reproductions, usually made on paper. Although the reproductions may be discharged from the apparatus for collection at any point accessible A. may consist of a transparent plate member such as, for example, a glass plate or the like positioned parallel to the externally of the machine, it is preferred that the discharge top of the desk, which is adapted to support a master or original, such as book 18 placed face downward on its terminal of the reproduction or paper feed means be em upper surface, the copyboard being uniformly illuminated bodied in a super-structure 4 overhanging the rear portion and arranged in light-projecting relation to the moving of the desk top, said super-structure also housing the main control panel 3 of the apparatus. Thus the document light-receiving surface of the xerographic drum 20. Uni form lighting is provided by a pair of lamps attached to holder or copyboard 5 and its covering platen 6 can be a slotted light re?ector mounted for movement to traverse left unobstructed at the front part of the desk over the 10 the plane of the copyboard. knee space. In the lower right-hand corner of the desk is a second control panel 7 for additional control circuits and for A light shield adapted to protect the xerographic drum from extraneous light is positioned adjacent to the surface, of the xerographic drum. A slot aperture in the light levers to control the length of scan, to control the ten shield extends transversely to the path of movement of sions of the paper separator rollers on a stack of paper 15 the light-receiving surface of the xerographic drum 20 to adjust for different paper weights, and for controlling to permit re?ected rays from the copyboard to be di-‘ the toner dispensing rate of the machine. As shown schematically in FIG. 1, the xerographic rected against a limited transverse area of the light-receiv ing surface as it passes therebeneath. As shown, the light apparatus comprises a xerographic plate including a photo shield also encloses the corona charging device 22. conductive layer or light-receiving surface on a conduc To enable the optical system to be enclosed within a tive backing and formed in the shape of a drum, generally conventional-size desk, a folded optical system including designated by numeral 20, which is mounted on a shaft an object mirror, a lens, and an image mirror is used in journaled in a frame to rotate in the direction indicated, the preferred embodiment of the apparatus. by the arrow to cause the drum surface sequentially to The lens element positioned between the copyboard pass a plurality of xerographic processing stations. 2 5 and the light shield is arranged for movement in a path For the purpose of the present disclosure, the several to traverse the plane of the copyboard in timed relation xerographic processing stations in the path of movement of the drum surface may be described functionally, as to the movement of the light source, whereby the subject image of the original supported by the copyboard is follows: i scanned in timed relation to the movement of the light A charging station, at which a uniform electrostatic 30 receiving surface of the xerographic drum to project a charge is deposited on the photoconductive layer of the light image corresponding to the subject image onto the xerographic drum; . surface of the xerographic drum. An exposure station, at which a light or ‘radiation pat Adjacent to the exposure station is a developing station tern of copy to be reproduced is projected onto the drum C, in which there is positioned a developer apparatus 26 surface to dissipate the electrostatic charge on the drum 35 including a casing or housing having a lower or sump por surface in the exposed areas thereof and thereby form tion for accumulating developing material 30. A bucket a latent electrostatic image of the copy to be reproduced; type conveyor having a suitable driving means, is used A developing station, at which a xerographic develop— to carry the developing material to the upper part of the ing material including toner particles having an electro developer housing where it is cascaded down over a hop static charge opposite to that of the electrostatic latent 40 per chute onto the xerographic drum. image are cascaded over the drum surface, whereby the As the developing material is cascaded over the xero toner particles adhere to the electrostatic latent image to graphic drum, toner particles are pulled away from the form a xerographic powder image in the con?guration 'of carrier component of the developing material and de the copy to be reproduced; posited on the drum to form powder images, while the A transfer station, at which the xerographic powder partially denuded carrier particles pass off the drum into image is electrostatically transferred from the drum sur-' the developer housing sump. As toner powder images face to a transfer material or support surface; and, are formed, additional toner particles must be supplied A drum cleaning and discharge station, at which the to the developing material in proportion to the amount drum surface is brushed to remove residual toner parti of toner deposited on the drum. For this purpose, a toner cles remaining thereon after image transfer, and at which the drum surface is exposed to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge remaining thereon. The charging station is preferably located as indicated by reference character A. In general, the charging ap paratus or corona charging device 22 includes a corona discharge array of one or more corona discharge elec trodes that extend transversely across the drum surface and are energized from a high potential source and are substantially enclosed within a shielding member. Next subsequent thereto in the path of motion of the xerographic drum is an exposure station B. This exposure station may be of one of a number of types of mecha nisms or members such as desirably an optical scanning or projection system or the like, designed to project a line copy image onto the surface of the photoconductive xero graphic drum from a stationary original. To permit dispenser, generally designated 28 of the type disclosed in copending Hunt application, Serial No. 776,976, ?led November 28, 1958, is used to accurately meter toner to the developing material. Positioned next and adjacent to the developing sta - ‘tion is the image transfer station D which includes a sheet feeding mechanism adapted to feed sheets of paper successively to the xerographic drum in coordination with the presentation of the developed image on the drum at the transfer station. This sheet feeding mechanism, generally designated 32, includes a sheet source, such as a tray, for a plurality of sheets of a suitable transfer material, that is, typically, sheets of paper or the like, a separating roller adapted to feed the top sheet of the stack to feed rollers which direct the sheet material into contact with the rotating drum at a speed preferably magazines and other types of cumbersome three-dimen sional objects to be copied for the reproduction of speci?c slightly in excess of the rate of travel of the surface of the drum in coordination with the appearance of the developed image at the transfer station. In this manner, the sheet material is introduced between the feed rollers information contained thereon, the optical projection sys and is thereby brought into contact with the rotating substantially any type of original copy, including books, tem shown is of the type disclosed in copending Mayo ap drum at the correct time and position to register with plication, Serial No. 783,388, ?led December 29, 1958. the developed image. The optical scanning or projection assembly, generally designated 24, comprises a stationary copyboard 5, which the sheet transfer material with the feed rollers and to direct the sheet transfer material into contact with the To effect proper registration of 3,062,534 5 6 through the ?lter bag so that only clean air reaches the drum, suitable guides are positioned on opposite sides of the feed rollers. The transfer of the xerographic powder image from the drum surface to the transfer material is effected by rneans of a corona transfer device 34 that is located at or immediately after the point of contact between the trans fer material and the rotating drum. The corona transfer device 34 is substantially similar to the corona charging device that is employed at charging station A, in that it includes an array of one or more corona discharge elec motor-fan unit. Any residual electrical charge remaining on the xero CI graphic drum is'dissipated by light from a ?uorescent lamp mounted in a suitable lamp housing hinged to the dust hood, a starter being provided for energizing the ?uorescent lamp. Suitable drive means drive the drum, lens element, and slotted light re?ector at predetermined speeds, relative to 10 each other and included are means to return the lens ele ment and the slotted light re?ector to their respective traverse starting positions and means to effect opera tion of the bucket-type conveyor, toner dispenser, endless conveyor, vertical conveyor; the separating roller and feed her. In operation, the electrostatic ?eld created by the corona discharge device is effective to tack the transfer 15 rollers being controlled in a manner to permit the feed of a sheet of transfer material into registered contact with material electrostatically to the drum surface, whereby the developed image on the xerographic drum as it is the transfer material moves synchronously with the drum rotated through the transfer station. Stated in a different while in contact therewith. Simultaneously with the tack trodes that are energized from a suitable high potential source and extend transversely across the drum surface and are substantially enclosed Within a shielding mem ing action, the electrostatic ?eld is effective to attract the manner, a sheet of transfer material is advanced in time toner particles comprising the xerographic powder image 20 relation to the start of scan of the leading edge of copy. from the drum surface and cause them to adhere electro statically to the surface of the transfer material. Referring now to FIGS. 2 and 3, there is shown the general arrangement of the xerographic apparatus within Immediately subsequent to the image transfer station the desk. 1. As shown, there is provided a frame for supporting the components of the apparatus formed by a there is positioned a transfer material stripping apparatus or paper pickoff mechanism, generally designated 36, for 25 base plate 10 to which are mounted full front and rear plates 11 and 12, respectively, and partial plate 13. The removing the transfer material from the drum surface. plates are connected together and maintained rigidly in This device includes a plurality of small diameter, multiple spaced relation to each other by suitable tie plate, not outlet conduits of a manifold that is supplied with pres surized aeriform ?uid by a pulsator operated by a suitable shown. power means. The pulsator is adapted to force jets of 30 As shown in FIG. 2, the xerographic drum 20 is pressurized aeriform ?uid through the outlet conduits into mounted on horizontal driven shaft 81-16 and the drum is positioned on the exposed front face of front plate 11, contact with the surface of the drum slightly in advance with the vmajor xerographic components of the machine of the sheet material to strip the leading edge of the sheet material from the drum surface and to direct it onto mounted around the drum either on the exposed front face of plate 11 or between plate 11 and partial plate 15. an endless conveyor 38 whereby the sheet material is The main drive elements and controls for the xero carried to a ?xing device, such as, for example, heat fuser (t2, whereby the developed and transferred xero graphic components are mounted between front and rear graphic powder image on the sheet material is per plates 11 and 12, respectively, as shown in FIG. 3, and manently ?xed thereto. they include as major components thereof, a main drive After fusing, the ?nished copy is preferably discharged 40 motor MOT-1, a scan control mechanism 48 for op from the apparatus at a suitable point for collection erating the movable elements of the optical system 24, a externally of the apparatus. To accomplish this, there programmer 50 for actuating the operation of the paper is provided a vertical conveyor, generally designated 44, feed system 32 and paper pickotf mechanism 36, a clutch mechanism 52 for effecting alternate operation of the by means of which the copy is delivered to a copy holder or collecting tray positioned in a suitable super-structure re. Si separator and feed rollers in the paper feed system, and overhanging the rear portion of the desk top. a lever control system 54 for adjusting the length of scan, The next and ?nal station in the device is a drum toner dispensing rate, and separator roller tension. it is believed that the foregoing description is suffi cleaning station E, having positioned therein a drum cient for the purpose of this application to show the general cleaning device ‘46 adapted to remove any powder remain ing on the xerographic drum after transfer by means of 50 operation of the xerographic apparatus. For further de tails concerning the speci?c construction of the xero a rotating brush and whereby the xerographic drum is graphic copier-duplicator shown, reference is made to ?ooded with light to cause dissipation of any residual copending Mayo et al. application, Serial No. 824,500, electrical charge remaining on the xerographic drum. To remove residual powder from the xerographic drum, ?led July 2, 1959. Paper Feed System there is disposed a cylindrical brush rotatively mounted 55 on an axle. For collecting powder particles removed Referring now to the paper feed system, the sheet from the xerographic drum by the brush there is pro vided a dust hood that is formed to encompass approxi mately two-thirds of the brush area. To insure thorough cleaning of the brush a flicking bar is preferably secured to the interior of the dust hood adjacent the edge of the exhaust duct and in interfering relation with the ends of the brush bristles whereby dust particles ‘may be dis~ lodged therefrom. For removing dust particles from the brush and dust hood, an exhaust duct is arranged to cover a slot that extends transversely across the dust hood and is con nected to a ?lter bag in the ?lter box. A motor—fan feeding mechanism 32, positioned in the image transfer station D, for seriatim feeding of cut-sheet transfer material into contact with the xerographic drum so that the developed powder images on the surface of said drum may be transferred to the transfer material, consists of a tray for holding a supply of cut-sheet transfer material, separator rollers for separating a single sheet of transfer 65 material from said supply, feed rollers for feeding a single sheet into contact with the drum and means for coordinat ring the operation of the separator rollers and feed rollers to thereby feed a single sheet of transfer material into contact with the drum for proper registration of the pow unit, connected to the ?lter box, produces a ?ow of 70 der image on the drum onto the transfer material. air through the ?lter box drawing air through the area Referring now speci?cally to FIGS. 4 through 19, in surrounding the xerographic drum and the dust hood, clusive, the apparatus for feeding sheets of transfer ma the air entraining powder particles removed from the terial to the xerographic drum 29 in timed relation to the appearance of a developed image thereon includes a pair drum by the brush as the air ?ows through the dust hood. Powder particles are separated from the air as its ?ows 75 of forwarding or feed rollers 401 and 492, usually made 8 7 of rubber or similar material, mounted in cooperative relation to each other in front of guides 4&3 and 4% which direct sheets of transfer material forwarded by suitable set screws, not shown, extends from opposite sides of the back guideplate to support the margin guides said feed rollers into contact with the drum 2% at a point at or slightly in advance of the corona transfer device 34. Feed roller 401, which is a driven roller, is mounted To permit lateral adiustment of the margin guides, each 416 and 417, which are suitably bored to slide on the shaft. of the margin guides is bored, as shown in FIG. 11, to receive a detent 432, in the form of a ball, which is biased by spring 4-33 into one of the suitably positioned notches in position by shaft SE40 journaled in frame plates 11 formed in the shaft, whereby the margin guides can be and 13 and is driven by pulley 465 secured to the end of readily indexed by the operator into the desired position shaft 81-49. Feed roller 402, which is an idler roller, is mounted on shaft SSH-8 journaled at its ends in arms 10 for paper of various widths. To aid the operator to quickly and correctly position a 4% pivotally mounted on frame plates ill and 13, the feed stack of paper in the tray, the shaft 431 is provided at roller 4192 being yieldingly biased against the feed roller opposite ends with two duplicate scales for lateral posi 46d by means of springs 4-07 so that feed roller 402 is tioning of the stack, and the angle plate 414 is provided driven by frictional engagement with roller 4433. or with with a scale for longitudinal positioning of the stack, suit a sheet of transfer material interposed between said rollers. able index markers being provided on the margin guides A supply of cut sheet material that is, typically, sheets and on the back guide plate for the convenience of the of paper or the like, to be fed one at a time to the operator in determining the proper location of these feed rollers 401 and 482 is held in a paper tray 4% slid elements. ably positioned at the front of the machine between frame Side frictional retention of the stack, to permit single 20 plates 11 and 13. feeding of the sheets is obtained by means of pressure The paper tray, includes a base member 409 having pads 434, usually made of rubber or other suitable ma angle plates 413 and 414 secured thereon, as by welding, the angle plates being positioned with their upright legs terial, carried by the margin guides 416 and 417. The parallel to and adjacent the sides of the base member and with their lateral legs partially extending over the center pressure pads 434 are mounted in such fashion that they can be replaced wherever desired. Each pad is secured, as by cement, to a sheet metal carrier 435 having a bent upper hook portion adapted to be inserted through a suit able aperture in the bracket 436, whereby the carrier, with the pad thereon, is somewhat loosely secured to channel of the base member to form a slot 415. Sheets of paper or other material are positioned both longitudinally and laterally on the tray by means of margin guides 416 and 417 adjustably mounted on the tray by means of shaft 431 in a manner to be described. 30 permit slight movement of the carrier to adjust the pad against the side margin of the stack. The bracket, formed Each of the margin guides 416 and 417, formed com plementary to each other, is provided with an upright side leg, an upright back leg at right angles to the side leg to guide the side and back edge, respectively, of the paper, as a bent leaf spring, is secured at one end by screws 424 to the side of a margin guide with the free end The margin guides are adjustably positioned on the tray of the spring extending beyond the front of the margin guide in position to normally bias the pressure pad against the side margin of a stack. To facilitate the placing or removal of a stack of paper on the tray there is provided by means of a back guide assembly 418 adapted to be a cam 437 on lever arm 438 loosely journaled in suitable selectively positioned along the length of the tray. Back guide assembly 418 includes a back guide plate 419 4.0 free end of a bracket 436 can be cammed away from adapted to ride on the top surface of the tray and is cen tered on the tray by means of a depending narrow bar the side of a stack of paper by rotation of the lever arm by means of lever 439 secured at one end thereof. portion of the back guide plate which is adapted to ride To further assure the feeding of sheets singly from the stack of paper, there is provided a drag roller 441, that and a lateral extending leg adapted to rest on the top of the paper tray. slots formed in the side of the margin guide whereby the in slot 43.5. Leaf spring 421, secured to the bar portion, retains the back guide plate 419 on the tray, while the left hand edge of the bar portion is biased against the edge of left-hand angle plate 413 by means of leaf springs 422 secured at one end by screws 424 to the front of the back guide plate. The free ends of the leaf springs 422 are guided by means of a spring guide 423 secured to the I rear of the back guide plate by screws 424. To permit longitudinal positioning of the back guide plate on the tray, a latch 425 is pivotably mounted on a latch shaft 426 positioned in a suitable groove formed in the back of the back guide plate and secured thereto by shaft support blocks 427 secured by screws 424 ex tending through the shaft support blocks and threaded into the back guide plate. The latch 425 is provided with a leg portion, as seen in ‘EEG. 10, adapted to slide into the notched or indented portions of the right hand angle 63 plate 414, whereby the longitudinal position of the back guide plate can be maintained as desired. The leg portion of the latch 425 is normally biased upward into locking position in a notched or indented portion of the angle plate by means of a latch spring 423 positioned normal to leaf spring 421, both springs being held in position by is adjustably positioned, when in its operative position to rest on the top most sheet of the stack. To obtain this result the drag roller 441 is rotatably journaled on axle 442 secured at opposite ends in the ends of a pair of arm 443 rotatably mounted on shaft 431 on opposite sides of the back guide plate. The drag roller, preferably made as a solid piece, because increased weight of this mem ber is desired, is arranged in its operative position ad jacent the rear end of the stack so that, as the trailing edge of the top most sheet of the stack is advanced only a short distance from under the drag rollers, the drag roller will be immediately effective to place a drag resist ance on the next sheet to prevent its advance to any un desirable degree, by friction from the top most advancing sheet. When a stack of paper is to be inserted into the paper tray, the drag roller is moved out of the way to an inoperative position by merely rotating the arms around the shaft 431. To prevent the bottom sheet of the stack of paper from being inadvertently drawn forward by the feeding and separating rollers 451, pads 412, usually made of rubber or other suitable material, are provided at the front of the paper tray. Right-hand bracket 446 and left-hand bracket 447 connected to base plate 1d are adapted to support the back guide assembly the operator depresses the upper curved portion of the latch toward shaft 431 thereby 70 paper tray assembly by means of a pair of commercial type drawer slides 448. As shown in FIGS. 4 and 6, pivoting the latch about latch shaft 426 to disengage the male portions of the slides are secured to the angle the leg portion from the notched or indented portions of cover plate 429 secured by screw 424 to the underside of the back guide plate. When it is desired to move the the right hand angle plate 414. Shaft 431 mounted in the bored portion of the back guide plate 419, and secured in alignment therein by 75 plates 413 and 414, and the complementary portions of the slides are secured to the brackets 446 and 447. As shown, in FIG. 5, the paper tray is maintained in 3,062,534. 10 operative relation to the feeding and separating roller As shown, cam arm 494, having a cam riser at one for seriatim feeding of sheets therefrom by means of a spring detent assembly 449 fastened to channel 14, forming part of the desk frame, positioned on the under side of base plate 11). The spring detent engages a de pending leg 411 of the base member 41319 of the paper end thereof is secured at its opposite end, as by welding, tray. to sleeve 475 connected as described by means of arm shaft 481 and arm pins 482 to the arm 454, whereby movement of the cam arm 494 effects an equal move ment of arm 454. To effect movement of cam arm 494, as the paper tray 408 is moved into or out of its normal To feed sheets of transfer material one at a time from operating position, the cam follower 495 is secured to a the paper tray 4115 into the bite of the feed rollers, there cam follower support 496 ?xed to the vertical leg of is provided a paper feeding and separating means com 10 angle plate 413 of paper tray 498. prising intermittently driven rollers 451 ?xedly mounted Both the operation of the paper separator rolls 451 upon shaft 452 journaled in bearings 453 mounted in arm 454 adapted to swing about the axis of driven shaft 455. As shown in FIG. 14, the arm 454 consists of arm shells 456 and 457 butted together and held in place by screws 458 extending through the arm shells to be threaded into spacers 459. The means for driving the rollers 451 comprises pulley 461 secured to a conventional slip clutch 462, and pulley 463 mounted on shafts 452 and 455, respectively, and operatively connected together by means of timing belt and the paper feed roll 401 is effected by the clutch mechanism 52 of the invention actuated by a program mer 50 of the type disclosed in the referenced Mayo et a1. application. As illustrated in FIGS. 3, 4, 16, 17 and 18, clutch mechanism 52 which is mounted between frame plates 11 and 12, include a shaft SH-7 bored at opposite ends to receive bearings 5111 whereby the shaft is journaled for rotation on the reduced end portions of spindles 502 extending through suitable apertures in the frame plates 464. 11 and 12 and retained in place by screws 503. The slip clutch 462 permits the rollers 451 to be re Shaft SH—7 is connected operatively to the main drive tated either by timing belt 464 or by frictional contact motor MOT-1 of the machine by belt 504, which runs with a sheet of transfer material as it is pulled forward by 25 on compound pulley 505 ?xed to shaft SH—7 by pins 506 feed rollers 4111 and 4112. and on a pulley, not shown, connected to the motor. Shaft 455 which is journaled by bearing 465 in frame Mounted on the shaft for rotation relative to the shaft 13 and by bearing 466 in arm shell 456 is normally biased are a pair of clutch elements 511 and 512 forming a ?rst to the left as seen in FIG. 14, by means of spring 457 clutch element and a second clutch element, respectively, interposed between snap ring 468 on shaft 455 and shaft of the clutch mechanism. The clutch elements are ro encircling washer 471 butted against frame 13. As shaft tatably supported on the outer races of bearings 507 455 is forced to the left, the opposite or notched end of mounted in spaced relation on the shaft. The outer races the shaft is forced into the aperture in the end of shaft of the bearings are held against the bored shoulder por‘ SET-11 to engage drive pin 473 secured therein. As tions of the clutch elements by retaining rings 503 shown, in FIG. 15, shaft SH—11 which is journaled in bearings 464. positioned in frame 12 and in sleeve 475, has an intermittently driven pulley 476 secured thereon. Washers 4'77 and 475 ride against a shoulder on shaft SH-1ll to prevent axial movement of said shaft to the left as seen in FIG. 15. To adjust the pressure of rollers 451 on the stack of transfer material in paper tray 4198, the arm 454 is ?xed to one end of arm shaft 481, the opposite end of the arm shaft being notched to engage drive pins 452 secured to the counter-bored end of sleeve 475 journaled in frame 11, the sleeve being retained against axial movement to the right as seen in FIGS. 14 and 15 by snap ring 453 secured in a suitable groove formed in the sleeve. positioned in suitable annular grooves formed in the clutch elements. Clutch element 511 is provided with peripheral teeth and is in effect a drive pulley connected, as shown in FIG. 4, by timing belt 522 to driven pulley 476 to 40 operate the paper separator rollers 451. In a similar manner, clutch element 512 is also provided with peripheral teeth and is a drive pulley connected by tim~ ing belt 524 to driven pulley 4&5 to operate the paper feed roll 401. Mounted between the clutch elements, and adapted to coact therewith is a third clutch element or armature 514 forming with clutch elements 511 and 512 an electromagnetic clutch assembly. A spring tension sleeve 454, having gear 485 secured To permit the armature to rotate with the shaft while thereon by (pins) 479, is loosely mounted by a bearing 50 being free for relative movement with respect to the axis 464 adjacent sleeve 475 on shaft SH-ll, and is axially of the shaft, the armature is mounted on splined hub 515 aligned on the shaft by thrust bearing 486 abutting snap secured as by key 516 to rotate with the shaft. ring 487 positioned in a suitable groove on the shaft. Torque is applied by means of coil spring 488 secured at one end by spring pin 491 to sleeve 475 and at its op posite end to spring tension sleeve 454 by having the end of the spring forced into a suitable aperture in said spring tension sleeve. By rotating gear 485 by means of chain 485 operated in a suitable manner (not shown) by The second clutch element 512 and the adjacent face, right-hand face as seen in FIG. 17, of armature 514 are provided with annular friction pads 517 suitably secured thereon whereby the clutch element 512 is driven by the armature through contact of the annular friction pads. The armature, which is normally ale-energized, is biased into driving engagement with clutch element 512 by means of spring 518 encircling bushing 521 loosely a control lever of lever control system 54 in lower con‘ trol panel 7, roller pressure on the stack of paper in mounted on shaft SH-7. One end portion of the spring paper tray 4% can be adjusted by an operator to accorn' engages the shoulder of bushing 521 and the opposite end modate any weight paper used as a transfer material. portion of the spring engages the bored shoulder por lnterposed between rollers 451 and feed rollers 401 tion of armature 514. and 4112 there is provided, as shown in FIGS. 4 and 5, 65 The force of spring 518 should be su?icient to force the a pair of paper guides 492 and 493 supported at opposite armature into frictional driving contact with clutch ele ends by frames 11 and 15 to guide each sheet of trans ment 512 while still permitting the armature when ener fer material forwarded by rollers 451 into the bite of gized to overcome the force of the spring to operatively rollers 4-01 and 4112. engage the clutch element 511. To permit the rollers 451 to clear a stack of transfer To limit axial movement of the clutch assembly on material in paper tray 498, as the tray is moved to its the shaft SH~7, the inner race of the left-hand bearing normal operating position as shown in FIG. 4, or when 507 is positioned by retaining ring 525 mounted in a the tray is removed from its normal operating position, there is provided a cam arm 494 and cam follower 495 to pivot arm 454 to elevate the rollers 451. suitable groove provided in the shaft. The inner race of the right-hand bearing abuts bearing 526 riding against 75 thrust washer 527 positioned against the inner face of aosassa 12 f1 While the invention has been described with reference to a preferred embodiment of the paper feed mechanism disclosed herein, it is not con?ned to the details set forth since many modi?cations and changes will become ap parent to those skilled in the paper feeding art. This application is intended to cover such modi?cations or changes as may come within the purposes of the improve ments or the scope of the following claims. as frame plate 1.1. This structure also limits axial move ment of the shaft in one direction, while axial movement of the shaft in the opposite direction is limited by bear ing 526 mounted between the compound pulley 5tl5 ?xed to the shaft and thrust washer 527 positioned against the inner face of frame plate 12. The armature 51d, of conventional construction, is connected to a suitable source of power, as described hereinafter, through brushes 31 bearing on suitable col What is claimed is: lector rings 532 on the armature. 1. In a sheet feeding apparatus, the combination of a frame, Each brush, as shown in detail in FIG. 18, is slidably mounted in a brush guide 533 and connected to a con a feed tray mounted on said frame to support a stack ductive line of the electrical circuit by means of a ter of sheets, feed rollers journaled in said frame in position to re ceive a sheet from said feed tray, minal strip 534. The brush guide is mounted in a holder 535 and the terminal strip is inserted between a 15 ?at on the brush guide and the holder 535 in electrical contact with terminal 536 connected by wire 537 to the brush. The terminal 536 is positioned in counterbored to said feed rollers, threaded portion of the holder and held therein by a screw cap 538 so that the spring 541 encircling the wire will bias the brush into electrical contact with a collector ring. Both the holder 535 and screw cap 538 are made of a suitable dielectric material. The holders 535 ‘for the brushes are adjustably mounted in collars 542 secured to the turned up legs of 25 component bracket 543 mounted on the base plate 16 of the machine. Set screws 544 threaded in the collars are used to secure the holders adjacent to the collector rings in position for the brushes to contact the collector rings. In FIG. 19, there is shown a simpli?ed wiring circuit 30 to effect operation of the clutch mechanism. As shown, the armature of the magnetic clutch is connected in series a driven shaft journaled in said frame, a ?rst clutch element and a second clutch element mounted in spaced relation on said driven shaft for rotation relative to said driven shaft, said ?rst clutch element being operatively connected to said separator means, said second clutch element being operatively connected to said feed rollers, an armature connected to said driven shaft for rota tion therewith and positioned between said ?rst clutch element and said second clutch element for axial movement therebetween, spring means positioned to normally bias said armature into driving engagement with said second clutch element, with a normally open limit switch lLS to a suitable source of electric power. The limit switch lLS is closed, in timed relation to the 35 formation of an image on the Xerographic drum, to effect operation of the paper separating rollers and the feed rolls for feeding a sheet of transfer material into con tact with the xerographic drum in registration with the developed image on the drum as it is rotated through the transfer station. Any suitable mechanism may be used and energizing means positioned in electrical contact with said armature to sequentially energize said ar mature whereby said armature will move out of en gagement with said second clutch element and into driving engagement with said ?rst clutch element. 2. In a sheet feeding apparatus, the combination of a frame, a feed tray mounted on said ‘frame to support a stack of sheets, to actuate the limit switch, such as a programmer mecha nism 59 of the type disclosed in the referenced co-pend feed rolls journaled in said frame in position to re ceive a sheet from said feed tray, ing Mayo et al. application. Referring now to the operation of the clutch mechanism 52, the armature 5714 of the clutch mechanism is nor mally de-energized to enable the spring 518 to force the armature into frictional driving engagement with the clutch a separator means operatively connected to said frame in position to feed sheets seriatim from said feed tray 1 element 512 to drive the paper feed roll 401. 'When the limit switch llLS is actuated to energize the armature, the ‘ armature will move to the left, as seen in FIG. 17, against the force of spring 518, out of engagement with clutch element 512 and into driving engagement with clutch ele ment 511 to effect operation of the paper separator rollers 451. As the separator rollers 451 are driven, they for ward a sheet of transfer material into the V formed by rollers 4d} and 4%2, Where its forward motion is mo mentarily stopped. As the movement of a sheet of trans fer material under separator rollers 451 continues after the leading edge of the sheet has been stopped by rollers M31 and ‘H92, the sheet is buckled as the separator rollers continue to rotate. The rotation of the separator rollers is continued just su?iciently to buckle the paper whereby the resiliency of the paper forces the leading edge of the sheet into transverse alignment with the rollers 4'61 and 65 462, irrespective of its original alignment thereto, so that the sheet is forwarded by the feed rollers in correct align ment onto the drum. As the actuating force on limit switch lLS is removed to open the circuit, the armature is de-energized, permitting it again to engage clutch ele ment 512 through the biasing action of spring 518 to operate feed roll 401 which in cooperation with feed roll Hi2 advances the sheet into contact with the xerographic drum. 75 a separator means operatively connected to said frame in position to feed sheets seriatim ‘from said feed tray to said feed rollers, a driven shaft journaled in said frame, a ?rst clutch element operatively connected to said separator means, and a second clutch element operatively connected to said feed rollers, said ?rst clutch element and said second clutch element being mounted in spaced relation on said driven shaft for rotation relative to said driven shaft, an armature connected to said driven shaft for rota tion therewith and positioned between said first clutch element and said second clutch element for axial movement therebetween, spring means positioned to normally bias said arma ture into driving engagement with said second clutch element to drive said feed rollers, and energizing means positioned in electrical contact with said armature to sequentially energize said ar mature Whereby said armature will move out of en gagement with said second clutch element and into driving engagement with said first clutch element to actuate said separator means. 3. In a sheet feeding apparatus, the combination of a ‘frame, a feed tray mounted on said ‘frame to support a stack of sheets, feed rollers journaled in said frame in position to re ceive a sheet from said feed tray, 3,062,534 14 13 a separator means operatively mounted on said frame in position to feed sheets seriatim from said feed tray to said feed rollers, a driven shaft journaled in said frame, a ?rst clutch element and a second clutch element mounted in spaced relation on said driven shaft for rotation relative to said driven shaft, said ?rst clutch element being operatively connected to said separator means, said second clutch element being operatively connected 10 to said feed rollers, 21 splined ‘hub ?xed to said driven shaft between said ?rst clutch element and said second clutch element, an armature movably connected to said splined hub for axial movement between said ?rst clutch element and said second clutch element, spring means positioned to normally bias said arma ture into driving engagement with said second clutch element, and electrical circuit means positioned in electrical con tact with said armature to sequentially energize said armature whereby said armature will move out of engagement with said second clutch element and into driving engagement with said ?rst clutch element. No references cited.